[gordon]

I think it IS a Weasel.

It has had all the upper bodywork removed, the controls and panel relocated, and the tracks and drive sprocket have been altered. I'd guess the body alterations were done first, and the tracks and drive have been changed over the years when the originals gave up.

The bottom of the hull, engine, drivetrain (presumably) four sets of bogie suspension, all look to be just cut down Weasel.

A sort of French version of the Strickland Bren Tractor, really.